You can model using pretty much whatever program you want. However, only max 6 - 9 works with exporting to BF2, aswell as some Maya versions (can't remember which, but not the newest). However, if you use features specific to newer versions, you won't retain all data. However, there shouldn't be any problems here, as newer max versions don't actually change the core data which is exported into BF2 anyway.

Oh don't quote me on the max 6 - 9, it may be working from 5 or 7, can't remember. Max 9 seems to be the standard within modding though. Not 2009, but 9.